This invention relates to a sound signal recording and reproducing device for use in a picture recording and reproducing apparatus such as a video taper recorder, and more particularly to a sound signal recording and reproducing device which can perform the function of the so-called after-recording such that a second sound signal is recorded on a recording medium while a recorded picture signal is being reproduced, in addition to its primary function of recording a sound signal in concurrent relation with recording of a picture signal on a recording medium.
In a magnetic tape recording and reproducing apparatus of the helical scan type, a sound signal is generally recorded on and reproduced from a sound track formed by a stationary head on an end portion of a magnetic tape. Especially, in the case of a home-use magnetic tape recording and reproducing apparatus, the recordable time with a fixed tape length is desirably as long as possible. To this end, a method is commonly employed in which the traveling speed of the magnetic tape is slowed down, and the width of the picture signal recording track is narrowed. Such a tendency of slowing down the tape traveling speed will continue in the future in view of the strong demand for the miniaturization of the apparatus of this kind.
However, the slowdown of the tape traveling speed leads to such problems among others that the frequency band of the sound signal recorded and reproduced by the stationary head is greatly decreased, and the wow-flutter characteristic is also deteriorated. Further, an attempt to narrow the gap length of the sound head for the purpose of improving the frequency characteristic results in a reduction of the efficiency of recording and reproduction, and this reduced efficiency gives rise to deterioration of the S/N ratio of the reproduced signal.
A method of recording a sound signal on the picture signal recording track in superposed relation with a picture signal can be utilized for the purpose of solving the problem of deterioration of the quality of sound due to the lowered tape traveling speed. According to this method, a rotary head is used for recording the picture signal, and, therefore, the speed of the rotating head is dominant between the relative speeds of the head and the magnetic tape. Thus, when the sound signal is recorded on the magnetic tape in superposed relation with the picture signal, the reproduced frequency band of the sound signal is not dependent upon the traveling speed of the magnetic tape, and the frequency band can be widened. Further, even when the time base of the reproduced sound signal may be subject to a variation, wow and flutter due to the tape traveling speed is almost negligible. In addition to the advantages described above, the desired S/N ratio can be fully ensured.
However, in the above method of recording the sound signal in superposed relation with the picture signal, it is natural that the sound signal must always be recorded in concurrent relation with the picture signal. According to the above method, therefore, it is impossible for the user to additionally record a second sound signal such as an explanation of scenes on the magnetic tape while observing the reproduction of the recorded picture. (This additional recording will be referred to hereinafter as after-recording.)